The invention relates to motor vehicles in general, and more particularly to improvements in motor vehicles with power trains which embody automated transmissions and/or automated torque transmitting systems. The invention also relates to improvements in methods of operating motor vehicles which embody power trains of the above outlined character.
It is known to provide a motor vehicle with an electronic, mechanical or fluid-operated actuator for an automated torque transmitting system, such as a friction clutch, a magnetic powder clutch or a hydrokinetic torque converter with a bypass or lockup clutch. An automated torque transmitting system (hereinafter called clutch or friction clutch for short) can be installed between the prime mover (such as an internal combustion engine or a hybrid structure employing an electric motor) and the (manual, automated or automatic) change speed transmission or between the output element of the transmission and one or more driven units (e.g., a differential). The so-called actor of the actuator for the clutch can transmit motion to a fork, lever, bearing or any other suitable component which serves to partially or fully engage or disengage the clutch.
The actuator receives, or can receive, signals from one or more sensors, switches and/or electrical or electronic circuits and processes such signals to operate the aforementioned actor which selects the condition (i.e., the extent of engagement or disengagement) of the clutch accordingly. The circuit(s) which is(are) operatively connected with the actuator can include an electronic circuit for the prime mover in the power train of the motor vehicle; such circuit can control or regulate the torque which the output element of the prime mover transmits, e.g., to a single or to a composite flywheel of the clutch.
The vehicle can be caused to carry out a so-called creeping (i.e., slow or gradual) movement in response to appropriate engagement of the clutch while the engine is on. If such creeping movement is caused to take place while the gas pedal is not depressed, while the transmission is in a gear other than neutral, and while the vehicle brake(s) is(are) not operated, this affects the engine in that the engine is stressed and its output is reduced at an inopportune time. This, in turn, entails a reduction of the RPM of the engine below the idling RPM before the idling speed regulator of the engine control electronics can effect an increase of the rotational speed back to the desired or optimum idling RPM.
The just outlined inopportune stressing of the engine, the resulting reduction of the engine RPM, and the subsequent increase of such RPM (e.g., to the desired or required idling RPM) are highly undesirable on several grounds. For example, such variations of the engine RPM can result in the generation of readily detectable noise and can also be a cause of other discomfort to the occupant or occupants of a motor vehicle and/or can affect the fuctioning or operation of the motor vehicle.